Apparatus for the recovery of byproducts of coking ovens



Feb. 29,-1944. F. A, WEBER 2,343,034

APPARATUS FOR THE RECOVERY oF Bar-PRODUCTS oF coKING ovENs Filed Dec.27. 1940 g M lgagwww 'y l?) lmefdo; WEBER,

Patented Feb. 29, 1944.

UNITED STATES PATENT. OFFICE- APPARATUS FOR THE RECOVERY F BY- PRODUCTS0F COKING OVENS This invention relates generally to improved apparatusand method employed in the recovery of by-product gases in the operationof coke ovens.

It relates more particularly to a new and improved type of injectornozzle adaptedvfor use in the recovery of ley-product gases which arelikely to form gummy tar-like or carbonaceous deposits on surfacesexposed to contact with such gases. More specifically it relates to animproved steam injector and method of using the same having means soarranged and constructed as to be capable of use and adjustment in sucha manner as to render impossible the formation of gummy or carbonaceousdeposition upon any surfaces nor--` mally forming a portion of theoutlet passage or channel for the steam injector, even when suchinjector is left in position with the nomle in the path andvexposed tothe byproduct gases, and even though the nozzle is not in active use.

Byreference to a condition referred to as not in active use. it isintended to mean the conditions -and time period under and during whichno steam is passing through the outlet passage or duct of the injectornozzle even though the nozzle is still retained in its position in thewall of the standpipe or other conduit through which the lay-productgases pass. l On the other hand, if through accident or over sight orimproper handling. there should be formed a -layer or deposit of gummyor carbonaceous deposit on the surfaces forming a part of the outletpassage or duct of the nozzle. and' thus tend to clog or obstruct -`suchoutlet passage in part or whole, the improved injector is. provided withself-cleaning means which may be employed for clearing any suchobstructing deposits from the outlet passage without the necessity ofdelay or loss of time in the charging' 'of the coking ovens which wouldotherwise occur, if it were necessary to' remove the steam injectornozzle for purposes of clearing any objec` tionable deposits abovereferred to.

Reference has been made to the two conditions when the steam injector isin use, and when it is not in use. The importance and pertinency ofthese distinctions will` beapparent because in the use of the steaminjector nozzle of the prior coking art and in the recovery ofby-product gases, no particular problem was presented during the periodofactive use, that is; during-the period when steam was passing throughthe nozzle outlet passage, because by reason of the force andtemperature of the steam during passagethrough the nozzle, it tended tokeep the nozzle passage clear and prevent the formation of any gummy orcarbonaceous obstructing deposits. either in part or whole, in suchoutlet passage.

The period in the coking cycle during which '5 the greater amount ofvolatile gases` are given of! and during which it is desirable to inducea draft by the steam injector nozzle t to carry of! the smoke and gasesto the gas collecting main, isv

during the period of charging the coke ovens or immediately after,charging of the ovens.'l It is during this initial period that the steaminjector nozzle finds its greatestv use. The use at this period tocarry' oil.' raw, more volatlleby-product gases to the collecting main,avoids thedischarge 1,, of such gases and coal dust to the atmosphereand thus avoids atmospheric pollution. Further,

I during this initial period, the formation of the gummy--orvcarbonaceous deposits is not so likely to occur as at a later period inthe coking cycle,

when the less vvolatile and heavier gummy and more stable products,which are more likely Ato form the objectionable obstructing' deposits'in the nozzle, require higher temperatures fand longer periods ofheating to carry them over from u the coke ovens through the standpipeand into the gas collecting main. Such heavier and less volatileproducts are. however. likely to condense or congeal as gummy ortar-like deposits on the nozzle upon reduction of temperature, duringre- '30 moval of the coke from the ovens.

There may be conditions under which gummy,

tar-like and carbonaceous deposits may accumulate upon the nozzleexposed to the gas and tend *u to obstruct the outlet opening in wholeor in part,

even while the nozzle is in use and whilev steam is being ejectedtherefrom. There may be other periods when it is not necessary to usethe nozzie, these latter conditions being'generally near the end of thecoking cycle when there are gen- 4|, rally. nov large volumes of smokyor more volatile gaseous products, and at thel completion of the vcoking period when the coke is removed from the ovens. The latter periodis accompanied with reduction of temperature. In either event, it isdesirable to be able to clear and clean the nozzle outlet of anyobstructing substance.

In accordance with the present invention the self-cleaning feature ofthe invention is obtained by providing a construction operable fromoutside of the standpipe and also of the injector, to entirely close orseal the steam outlet passage at its tip end which is the portion whichextends furthest within the standpipe passage. The sealing and closingof the tip end of the outlet pasn sage would of course be during aperiod of nonuse of the nozzle, but the nozzle itself would not beremoved but would remain in its position usually, in the standpipes orvalve-body connecting with the gas collecting main, so'that the portionof the nozzle exposed to the passage of the byproduct gases would stillbe subjected to the objectionable deposits from the gases passing to thegas collecting main. There is also provided in the device a closure orsealing member which moves axially within the outlet passage in contactwith the walls thereof to produce a. plunger or wiping effect to cleansethe walls of the outlet passage and the aperture of` any adhering gummycarbonaceous or other sustances obstructing the same in part or inwhole.

In locating prior art injector nozzles of the,

constantly open end type, such nozzles were usually disposed downwardlyin a downwardly directed dow of gases. Such an arrangement wasdesirable, if not essential, in order to avoid the gravity effect in anupwardly disposed nozzle, of any congealed, condensed or gummy deposits,

from being carried backward and downwardA within the inner aperture orchamber of the nozzle, particularly at such times when not in active useand steam was not issuing from the nozzle.

Such periods of non-use would include periods in which a reduction oftemperature would take place such, for example, as at the end of thecoking cycle, when the coke is being removed from the ovens. yAnydeposits congealed or condensed within the exposed outlet passage andaperture of the nozzle, or any liquid products which 'might have foundtheir way within the inner chamber or passage of the nozzle,particularly if the noz' zle were in a position in which the open endpointed upward, would tend to clog and obstruct the nozzle outletaperture and passage, in whole or part. It frequently has occurred whenusing nozzles of the prior art, that it was necessary to delay thecharging of the ovens in the continuous coking process, until theclogged nozzle had been removed and cleansed and again replaced. Suchdelays and loss of time are avoided by the employment of my improvednozzle with the self-cleaning device, together with the means forforming a complete seal and closure for the outlet passage. Anadditional advantage made possible by the employment of my improvednozzle, is that it enables the nozzle to be disposed in an upwarddirected flow or. path of gases, with the open ended tip of the nozzledisposed in an upwardly inclined direction when in use, without thehazard or danger of gummy or liquid deposits flowing backward ordownward by gravity effect, into the nozzle passages to clog the sameduring periods of non-use, because lof the facility with which the tipend of the nozzle may be sealed and closed against the entry of any suchobjectionable obstructing deposits. This self-cleaning and self-sealingfeature of the steam injector nozzle as aifecting'its disposition andarangement. has a very close relation in its cooperation and functioningwith other elements of the coking system conducting the by-productgases, particularly in the respect of enabling an induced draft to beeffected by a more direct, convenient and eilicient arrangement and'disposition of the standpipe, gas collecting main. and intermediateconnecting valve-body member. The valve-body structures of the priorart, in which the steam injector has been mounted in a substantiallyvertical position Y with the open end of the nozzle directed downwardlyand in a downwardly directed flow of gases, have been of a rathercomplicated` and involved structure and have included a reve sel! curvedneck or elbow, so that the gases were required to follow a rathertortuous path including substantially three right-angle bends or turns,in the path from the vertical standpipe connected with the coke oven tothe gas collecting main disposed horizontally and to one side of thestandpipe. By providing an improved nozzle such as that with theself-cleaning' and tip-sealing features disclosed herein, in which thenozzle may be mounted with the open tip end directed upwardly andlaterally, a direct connection may be made between the standpipe and thegas collecting main, by the employment of a valve-body of relativeVsimple construction and which employs only one substantially right-angleturn.

- The nozzle may be mounted in the outer wall of the standpipe and maybe mounted at such an angle at a point approximating one end of ahorizontal radial line of the right-angle bend in the connectingvalve-body member, so that a substantially direct line of flow iseffected from the nozzle tip across the right-angle elbow, and into thegas collector main, without the necessity of having to traverse areverse bend at the elbow as has been done in the prior art.

In the drawing, one selected embodiment is shown for purposes ofillustration of the improved type of nozzle and of the method in whichit may be employed in its relation with other elements used in thecoking process. It is understood that various changes in detail featuresand arrangement of elements may be made without departing in essentialrespects from this invention.

Figure 1 is a vertical section showing the general arrangement of partsincluding the upper portion of the coking oven, a standpipe, a gascollecting main, and a connecting valve-body with a steam injectornozzle therein for inducing a draft to carry off the by-product gasesfrom the coke oven to the gas collecting main.

Figure 2 is an enlarged section of the improved steam injector nozzleshowing the self-cleaning and tip-sealing features.

Figure 3 is a transverse section taken on the line and looking in thedirection of the arrow III-III of Figure `2.

Figure 4 is a fragment in section showing a lmodified form of the nozzlein which the stem is threaded in the nozzle.

In the drawing, a top fragment of a coke oven I is shown in section,such oven having the usual outlet passage 2 therefrom for carrying offthe by-product gases and other products through a standpipe shown asincluding a refractory lining 3 and surrounding metallic pipe I, thelower portion of said standpipe being connected to the oven in a mannerwell-known in the art by a usual collar 5 and seal 0. The gases areconducted from the standpipe through a substantially right-angle passageformed by a valvebody Il and into a gas collecting main 1 which is shownsupported in a horizontal position to one side of the standpipe uponsuitable beam structure I and bracket or cradle l above the oven I.

The valve-body III which serves as a connecting conduit for conveyingthe gases from the standpipe 4 to the gas collecting main 1, is providedwith a number of valves. One of said valves is shown as a flap type ofvalve Il which is hinged at one side and opens directly to theatmosphere and is disposed in the valve body in a substantially directline above the standpipe 4 it in position.

a,s4s,oa4

guided for movement axiallyof the nozzle in a f so that if'there is anyexcess of pressure developed within the gas passages for any reason,

'such pressure might be' released by exhaust of the gases directly tothe atmosphere. A second 1 butterfly type of valve I2 is shown in thevalvebody, such valve being disposed at 'a point between the valve |Iopening,to'the atmosphere, and the gas collecting main 1. Thedetailconstruction of these valves will not be elaborated upon at thispoint, because they are types of valves well known in the art.

In order to linduce a draft within the passag conducting the gases fromthe coke oven to the gas collecting main, a steam injector nozzle I3 isshown mounted in the outer wall of the valvebody I0. 'I'he tip end I1 ofthe nozzle I3 having the outlet aperture therein, is disposed in adibearing bushing 28 shown threaded in one end of the nozzle.y Ashoulder 21 on thefbushing serves as a stop Yto limit the movement` ofthe bushing 26 in thenozzle. Atthe outer-fend of the bushing, a` packing28 is provide'dfandis retained in position by the cap 29 threaded on thebushing 26 `in a manner wellknown Ithe art. A handlek 30 is provided atthe cute of the stem 22 for moving the stemZZaiciallyy of the nozzle.As'shown in Figure 2, this atifal movement would be oi.' a slidingcharacter.` As

' shown in Figure 4, a` modified form is disclosed rection upwardly andlaterally of the passage` from the standpipe, across the passage in thevalve-body In m a substantially direct diametric or chordal path to thegas' collecting main 1. Such an arrangement and disposition of thenozzle enables the laterally directed jet of gas or steam to be directedacross the diameter of the in which the stem 22 is provided with athreaded portion 35 which engages *a lcorrespondingly threaded portionin the bushing 26.

A means is provided vfor effectively forming a sealst the tip end I1 ofthevnozzle in order to 'prevent the formation of any gummy, tar-liketion of a sealing film across the nozzle outlet standpipe so as to forma blanket-like barrier protecting the elbow from the scouring and otherdeleterious eil'ects of the coking gases.

The location of the steam injector nozzle I3 at the position indicatedat the end of a substantially horizontal radius line of the valve-bodywhich conducts the by-product gases from the standpipe 4 to the gascollecting-main 1 by a single right-angle turn or deflection,contributes tol an effective and efficient transmission of the gases.The location of the steam injector nozzle I 3 at such a point enables aneffective suction or draft to be formed by substantially directdischarge of the by-product gases from the standpipe of the gascollecting main through a minimum distance. The reverse turn usuallyemor carbonaceous depositsE upon the walls 2| of the outlet passage ofthe nozzle I3, or the formaaperture 20, even though such lm may notactually nd its way as a deposit upon the inner walls 2| defining theoutlet passage. For this purpose, there is provided a forward plungerportion 3| of the stem 22 which snugly fits within the `outlet passageand forms a wiping contact with the walls 2| thereof. The outletaperture and the end plunger portion 3| of the stem 22 may be formed ofvarying shapes. The outlet aperture should be sealed only during periodsin ployed inA valve-bodies where prior art types of nozzles areemployed, is eliminated. In addition to the induced flow due to thevelocity effect of the steam issuing from the injector nozzle creat--ing dinerential pressure areas at the right-angle' turn, thesubstantially direct dischargel into the vgas collecting main 1 ofsubstantially klarger varea than a section of the standpipe and thevalvebody. is an additional factor which contributes to furtherexpansion of the gases and creation of additional draft effect.

The nozzle construction, as shown in mure 2,

which the nozzle is not actually being used, this period of non-usebeing, as` heretofore defined, those periods during which no steam isbeing ejected from the nozzle, even though the nozzle the shouldermerges into the end plunger portion 3| by a gradual taper or bevel seatwhich engages a portion of corresponding shape in the end wall of thechamber I8. y In addition to servcomprises an elongated-tapered bodyportion I3 having a chamber I3 therein extending longitudinally ofthenozzle portion and havingV an outlet passage or aperture 20 dened by thewalls 2| at the tip end I1 of the nozzle. Steam is conducted to thenozzle chamber I8 through thel steam pipe I5 which is shown threaded ina laterally disposed aperture at the opposite end of the nozzle. Thebody portion of the nozzle-at its opposite end is shown as'an enlargedportion. 34 in order to facilitate handling of the nozzle in placing itin position in the valve-body III, or other conduit, orinremoving ittherefrom. As shown, the nozzle I3 is retained in position in thevalve-body IIIl and is ntted in an enlarged boss or flanged portion I4byl a tight driving nt. If desired, the nozzle may be provided with athreaded portion to, engage a correspondingly ling as a cleansing means,such a sealing arrangement also serves as a valve function in cuttingoil' the supply of steam or other liquid which is being ejected from thenozzle. Such a valve function may be utilized as one supplementarythreaded portion of the vvalve-body for retaining A valve I8 may beprovided in the steam pipej'lt for controlling the supply of steam totheinozzl'e.- The nozzle isalso provided wltha stem 'portion 22 which issupported and to the main valve control I6 disposed in the steam supplyline I5 outside andindependent of the nozzle I3. One possible advantagein controlling the steam supply by the tip Asealing means is that onoccasions it may be ldesirableto maintain the temperature of the bodyportio of the-nozzle at the temperature of the steam even though steamis not actually being ejected from the nozzle. prevent the formation ofdeposits upon the nozzle by congeaiing or condensing, which might be thecase if the nozzle were of a lower temperature. Such an advantage couldnot be utilized, where the sole means of controlling the steam is from aseparate valve, such as a control valve I6 in the steam line I5 -at somedistance from the nozzle I3.

A means is also provided for limiting the axial movement .of the stem 22in the opposite outward Such a feature may serve to A direction. Forthis purpose there is provided a second shoulder or stop portion 23having at one side thereof a face portion which tapers or merges intothe stern portion 22 and engages or seats within a correspondinglyshaped portion in the end of the bushing 26. Preferably the diameter ofthe shoulder portion 23 is larger than the shoulder stop 24 adjacent theother end of the stem, oneadvantage of such a difference in the size ofthe respective shoulders being that the fluid ow or pressure actingagainst the face 23' of the shoulder 23 would serve as a means ofretaining the stem at its outward limit of travel, without the necessityfor other locking or holding means, in the event that the frictionalengagement of the stem with its bearing bushing 26 or packing 28 werenot suillcient for this purpose.

As shown in Figure 2, the laterally disposed steam inlet aperture i9within the enlarged pori tion 34 of the nozzle body is at a pointadjacent the location of the shoulder 23 upon the stem 22, the relativearrangement and positioning of the inlet aperture and the exposedtapering face 23' of the stop 23 being subjected directly to the ilow ofsteam as it issues from the steam pipe I5 into the enlarged chamber 32at the outer end of the nozzle chamber I8. By varying the relative sizesof the two stops 24 and 23, the relative diameters of the nozzlechambers I8 and 32, respectively, in which they are positioned, and byalso varying the axial extent of the enlarged chamber 32 relative thedistance that the end of the plunger 3i is required to travel beforeentering the outlet aperture 20, so as to permit the enlarged shoulder23 to move within the restricted chamber I8, a control element or meansis utilized for varying the pressure or velocity of steam between thepoints of either all on" or all off. The nozzle as herein shown anddescribed is employed in the method of coking coal and the recovery ofby-product gases and other products. However, a nozzle of this characterhaving a self-cleaning and sealing means and also a capability ofvarying the pressure and quantity of liquid ejected, may be of usein-the spraying of other liquids, such, for example, as tar, which has atendency to deposit in the tip of the nozzle and ca rburize if subjectedto heat, and to cause a change in the size of the nozzle opening whichis generally of a very small diameter. The facility for self-cleaning ofthe nozzle, without requiring the removal or disassembly of the nozzle,in order to clean the outlet passages, is a feature of considerableadvantage.

While one preferred form of apparatus and one particular relation anddisposition of elements has been shown in the application to the cokingprocess, and the recovery of by-products has been shownl and describedherein, it is understood that details of certain parts and modifiedarrangements may be made within the knowledge Kof those familiar withthe art, without departing from the spirit of the invention.

I claim:

1. In mechanism for injecting steam in the byproduct coke oven gasesconveyed from the oven through a standpipe during the oven-charging'period to a gas collecting main disposed to one side of and onsubstantially the same level as the upper end of said standpipe toinduce a flow and formation of any such deposits on the walls' cluding astandpipe and a self-cleaning hand actuated steam injector nozzlemounted at the upper end of said standpipe in the'outer wall of theright angle elbow so as to discharge a jet of steam within saidstandpipe laterally and slightly upwardly thereof at and across theupper end thereof to form a protective and deilecting blanket, into andat the elbow, at which portion the path of the gases is abruptlydeflected by the blanket-like jet laterally across the diameter thereof,and from the standpipe to the gas collecting main whereby differentialpressure areas are formed at the elbow within the path of gas travelbefore the coke oven gases reach the elbow which induces passage of theby-product gases from the standpipe directly by a single right angledturn in to the gas collecting main without requiring or necessitatingdischarge of gaseous, smoky or ignited products to the atmosphere.

2. In a by-product coke oven manually actuated self-cleansing steaminjector nozzle adapted to be employed in by-product gases likely toform hardened gum and carbonaceous deposits on surfaces oi the nozzleoutlet passage exposed to the gases, said self-cleaning steam injectornozzle i including a hollow cylindrical body portion having alongitudinally extending chamber, a tapering nozzle portion at one endand a restricted cylinder-like outlet passage therein of uniformcross-section, an inlet passage leading to said chamber and a valve forsaid inlet, a longitudinally movable stem member mounted to slidelongitudinally of said chamber, the extreme outer end of said stem beingplunger-like and of uniform cross-section throughout its lengthextending to the end thereof and adapted to fit snugly within and have awiping contact throughout the extent of the cylinder-like outlet passagefor the full length thereof and for a distance extending to the extremeouter end of the cylinder-like outlet `passage and of the nozzle toclear the same of any accidentally accumulated deposit of gummy orcarbonaceous matter and to prevent the entry of the outlet passage whenthe end of the nozzle is in the path of the by-product gases duringsuchperiods of coking when no steam is being ejected from the nozzle toexert a cleaning eileot whereby there is eliminated loss of timeincident to the necessity of removing a wholly or partially cloggedsteam injector nozzle for purposes of cleaning or repair.

'3. In a by-product coke oven, in combination, an up standpipe,4 a.self-cleansing steam injector nozzle adapted to be employedin'by-product l gases likely to form hardened gum and carbonaceousdeposits on surfaces of the nozzle outlet passage exposed to the gasesin said standpipe,

' a hollow cylindrical body portion having a longitudinally extendingchamber, a tapering nozzle portion at one end and a restrictedcylinder-like outlet passage therein of uniform.crosssection, an inletpassage leading to said chamber at the other end and .extendinglaterally thereof a bearto said gas collecting main. said mechanismining bushing removably secured in the chamber at the end adjacent theinlet, a longitudinally movable stem member guided in said bushing andactuatedfrom outside said nozzle, the extreme outer end of said stembeing plunger-like and of uniform cross-section throughout its lengthextending to the end thereof and adapted to flt snugly within and have awiping contact throughout the extent of the cylinder-like outlet passagefor the full length thereof and for a distance extending to the-extremeouter end of the cylinderlike outlet passage and of the nozzle to clearthe same of accidentally accumulated deposit of gummy or 'carbonaceousmatter and 'whereby there. is eliminated delays in the functioning ofthe coking oven during a charging period and loss of time incident t thenecessity of removing a wholly or partially clogged steam injectornozzle for purposes of cleaning or repair.

4. In mechanism for by-product gas recovery from coke oven operationincluding in combination a standpipe, a gas collecting main, and asingle right angle elbow valve body, in the path of the gases conductedby said standpipe to said gas collecting main causing a change indirection of gas movement and a disposition to formation of turbulenceand eddy currents at said elbow, including a ilat type of valve, openingdirectly to the atmosphere, means for inducing a ilowpf by-v productgases from said standpipe directly to said gas collecting main and inminimizing the tendency to form turbulence andeddy currents at theelbow, said means including a Vmanually vactuated self-cleaning steamnozzle, mounted in the outer wall of the standpipe adjacent the elbow toform a steam jet substantially horizontally and laterally of, and withinand across the diameter of the vertical standpipe at the elbow, andbefore said gases reach the ilap type valve in the 4valve body, wherebythe gases together with the steam and any condensed moisture are inducedto flow directly into the gas collecting main by a single substantiallyright angle deflection from the upward direction of gas flow in thestandpipe, and whereby the -laterally directed jetof steam forms ablanket-like protection of the elbow from the scouring and otherdeleterious action of the coke oven gases.

5. In mechanism for inducing circulation cf by-product gases from a.vertical standpipe to a gas collecting main in the operation of cokingovens, the combination including a verticalstandpipe, a steam injectornozzle mounted in the outer wall of said standpipe most distant from thegas collecting vmain and having the delivery end of said nozzleextending through said outer wall oi' said standpipe so as to besubjected to the byproduct gases said nozzle including an elongatedbody-and chamber therein, an outlet passage of uniform cross-sectionthroughout its length' and terminating in the tip end of the nozzleexposed to said gases which are disposed to form gummy or carbonaceousdeposits on surfaces exposedthereto and closure means including aplungerlike section of uniform cross-section adapted to t snugly, with awiping contact within and throughout the extent of the outlet passageand movement therethrough for sealing the outlet passage when steam isnot being ejected there` from to prevent the formation of any gummy orcarbonaceous deposits within said outlet passage or on the walls thereofwhich would cause restriction thereof and interfere with the flow ofsteam therefrom.

6. In mechanism for inducing circulation-of by-product gases from thestandpipe to the gas collecting main in the operation of coking ovens.

said mechanism including a standpipe, a steam injector nozzle adapted tobe mounted in said standpipe and having the delivery end of said nozzleextending through the walls of said standpipe so as to be subjected tothe by-product gases including an elongated body and chamber therein, anoutlet passage of uniform. size and section throughout in the tip end.of. the nozzle exposed to said gases in the standpipe which are disposedto form gummy or carbonaceous depositson surfaces exposed thereto, andclosure means for sealing the outlet passage, said closure meansincluding a stem mounted for movement axially of stem in each direction,a steam inlet passage iaterally disposed at the outer end ofthe'lnozzle,

'the larger of said stops being disposed on the stem at a point adjacentsaid steam inlet whereby the ow of steam at the .inlet point iseffective upon said larger disk-stop to hold the stem in an openposition, with the disk-like stop in abutting rela- K tion with the stembearing guide, the second disklike stop being spaced from the other endof the stem and adapted to limit the outward movement of the end of thestem through the outlet passage when clearing the same of anyobstructingl material, the movement of the end of the stem outward beingsuch as tomove the larger disk-like stop member through and past theincoming flow of steam in the inlet passage and to cause such steam flowto exert a pressure on the opposite side of the larger disk-like stopand to urge movement of said stem in the opposite direction.

'1. In mechanism for inducing circulation of byproduct gases from thestandpipe to the gas collecting main, said mechanism including astandpipe, a steam injector nozzle adapted to be mounted in saidstandpipe and having the delivery end of said nozzle extending throughthe walls of said standpipe so as to be subjected to the by-productgases including an elongated body and chamber therein, an outlet passageof uniform cross section in the tip end of the nozzle exposed to saidgases in the standpipe which are disposed to form gummy or carbonaceousdeposits on surfaces exposed thereto, and closure -means for sealing theoutlet passage, said closure means including a plunger-like stem ofuniform cross section,corresponding to that of the outlet passagemounted for movement axially of the nozzle and adapted to fit snuglywithin the outletv the second disk-like stop being spaced from the otherend of the stem and adapted to limit the outward movement ofthe end ofthe stem through the outlet passage when clearing the same of anyy FREDA. WEBER:

obstructing material.

